i strongly recommend a series hybrid diesel generator powers battery bank which powers electric motor to rear wheel why first its actually easier the whole generatorengine assembly can be bought off the shelf and you dont need a tranny with an electric motor it has full torque from rpm second a diesel motor has a narrow powerband but within a very narrow rpm window it is in its happy place where fuel economy is awesome thats why they make killer genset motors this is how a dieselelectric submarine and locomotive work